They have sensory organs and weak points in this edition. They can be sneak attacked. Knocked prone must be what happens when they are rolled over on their ocular organ with their mobility/reproductive organ sticking in the air (how embarrassing) and their grabbing/eating organ flailing off to the side.
Yes, or rather:Can slimes or oozes be knocked prone?
This happened to my aunt once, it's actually really serious.
Poor Aunt Bertha...
Someone tipped her?